manuals:networking:delta-fiber-ftu

At my house, I have two fiber connections. One from KPN NetwerkNL (previously known as Reggefiber) and one from Delta Fiber (previously known as CAIW). The KPN network is by far the most widespread, and therefore has most readily-available components to be found easily. NTU's, patch covers, and so on can be found new and second hand at many places.

Currently, my Freedom Internet subscription enters my house through the KPN fiber. I use a ZTE ZXHN F3100 NTU in order to connect to my router. Information about this setup can be found here.

However, Freedom Internet is also working on the availability of their service on the Delta Fiber network. I would certainly welcome this, because that would allow me to have a second subscription and realise a dual WAN setup that could automatically fail over.

Contrary to KPN NetwerkNL, for which we can easily get media converters and patch covers, Delta Fiber's appliances are less well documented and far less circulating on the second hand market. So that means that I had to build a patch cable and media converter myself.



Delta Fiber uses an Attema FTU, apparently type “AT29100”. It has two SC/APC connectors internally, with two bottom-sliding cradles which are empty by default.

We'll have to add a patch cable with an SC/APC connector to the slider cradle of the left connector. The other side of that cable will go into an SFP module, which will most likely have an LC/PC connector. So it's best to buy a cable that has an SC/APC connector at one side and an LC/PC connector at the other. You need a single mode 9/125 simplex cable. I got this one.

When you have the cable ready, remove the left cradle by pulling the tab towards you and then pulling it down. Once it's out, you'll see that it consists of three plastic parts, that you can detach by pushing some tabs.

First run the cable under the small plastic cover and then click it back into place. Don't mind the orientation of the connector yet. Then turn the largest part around and place the SC/APC connector in there. Look carefully at the photo. You'll see that the part is asymmetric. The plastic ledge on the bottom is larger than the one on the top. The orientation tab of the connector has to go on the side of the longer plastic ledge.

Click the cradle back together. The result should look like the following pictures. When holding the cradle up, as if you were to slide it in the FTU, the tab on the SC/APC connector has to point to the right.

Don't forget to remove the plastic dust cover from the SC/APC connector. Then slide it in the FTU and push until you hear a click. You may have to push the cradle a little, but excessive force should not be needed. If the cradle stops at about 1 centimeter before fully inserted, you probably put the SC/APC connector in the wrong orientation. Check the cradle to make sure the tab points right.



You need a 1000Base-BX-10-U SFP which transmits on a wavelength of 1310 nm and receives on a wavelength of 1490 nm or 1550 nm. A TP-Link TL-SM321B should work, and is pretty easy to find. In case your router has an SFP slot, you can insert the module directly into your router. In case it does not, you'll need a media converter that can hold the SFP module and convert the optical signal to an electric ethernet signal and vice versa. For instance, you could use a TP-Link MC220L.

Remove the plastic dust cover from the LC/PC connector and put it in the SFP module. In case the SFP module is in a media converter, connect the ethernet port to your router's WAN port. That should be all.


  • manuals/networking/delta-fiber-ftu.txt
  • Last modified: 2021/07/18 10:34
  • by Kevin Keijzer